1. Field of the Invention
The present invention relates to an electrostatic latent image developing toner.
2. Description of the Related Art
Recently, in the field of electrostatic latent image developing toners, along with demands for high image quality in the market, suitable electrophotographic apparatuses and toners usable in such apparatuses have been developed rapidly. For example, with respect to the toners that meet the demands for high image quality, the sharpness in the particle-size distribution is required. When the particle size of a toner is uniformly adjusted with a sharp particle-size distribution, developing behaviors of individual toner particles are uniformly adjusted so that a great improvement in the fine-dot reproducing property is achieved. In this case, however, it is not easy to achieve a sharp toner particle-size distribution. Here, an emulsion polymerization aggregating method has been proposed as a manufacturing method in which the shape of toner particles and the particle-size distribution are made desirably controllable. In this method, a polymer primary fine particle dispersion solution is preliminarily prepared through an emulsion polymerizing process, and a colorant fine-particle dispersion solution and a wax dispersion solution or the like, if necessary, are prepared in a separate manner, and while these solutions are mixed and stirred, with a suitable flocculant such as inorganic metal salt being added thereto so as to aggregate, and this is then heated so that the polymer resin is fused and adhered to obtain toner particles.
There have also been strong demands for energy-saving electrophotographic apparatuses, and since high energy is required for toner fixing processes, there have been strong demands for a low-temperature fixing property in a toner. Because of current demands for high-speed and space-saving copying machines, toners having a superior low-temperature fixing property have been demanded.
The thermal fusing property relating to a toner fixing function greatly depends on the thermal property of a binder resin to be used, and in order to lower the fixing temperature, it is necessary to lower the melting point and melt viscosity of the resin. However, when the melting point and melt viscosity of the binder resin are lowered, new problems, such as degradation in the toner heat-resistant storing property and mechanical strength (stress resistant property) and degradation in the charge environmental stability, are raised.
At present, a toner capable of simultaneously solving such problems with low-temperature fixing property, heat-resistant storing property, mechanical strength and charge environmental stability has not been achieved.